﻿/*******************************************************************************
 * You may amend and distribute as you like, but don't remove this header!
 *
 * EPPlus provides server-side generation of Excel 2007/2010 spreadsheets.
 * See http://www.codeplex.com/EPPlus for details.
 *
 * Copyright (C) 2011  Jan Källman
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
 * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
 *
 * All code and executables are provided "as is" with no warranty either express or implied.
 * The author accepts no liability for any damage or loss of business that this product may cause.
 *
 * Code change notes:
 *
 * Author							Change						Date
 * ******************************************************************************
 * Mats Alm   		                Added       		        2011-01-08
 * Jan Källman		    License changed GPL-->LGPL  2011-12-27
 *******************************************************************************/

using System;
using System.Xml;

namespace AppsheetEpplus;

/// <summary>
/// Enumeration representing the state of an <see cref="ExcelDataValidationFormulaValue{T}"/>
/// </summary>
internal enum FormulaState {
  /// <summary>
  /// Value is set
  /// </summary>
  Value,

  /// <summary>
  /// Formula is set
  /// </summary>
  Formula,
}

/// <summary>
/// Base class for a formula
/// </summary>
internal abstract class ExcelDataValidationFormula : XmlHelper {
  /// <summary>
  /// Constructor
  /// </summary>
  /// <param name="namespaceManager">Namespacemanger of the worksheet</param>
  /// <param name="topNode">validation top node</param>
  /// <param name="formulaPath">xml path of the current formula</param>
  public ExcelDataValidationFormula(
      XmlNamespaceManager namespaceManager,
      XmlNode topNode,
      string formulaPath)
      : base(namespaceManager, topNode) {
    ArgumentException.ThrowIfNullOrEmpty(formulaPath);
    FormulaPath = formulaPath;
  }

  private string _formula;

  protected string FormulaPath { get; private set; }

  /// <summary>
  /// State of the validationformula, i.e. tells if value or formula is set
  /// </summary>
  protected FormulaState State { get; set; }

  /// <summary>
  /// A formula which output must match the current validation type
  /// </summary>
  public string ExcelFormula {
    get => _formula;
    set {
      if (!string.IsNullOrEmpty(value)) {
        ResetValue();
        State = FormulaState.Formula;
      }
      if (value != null && value.Length > 255) {
        throw new InvalidOperationException(
            "The length of a DataValidation formula cannot exceed 255 characters");
      }
      //var val = SqRefUtility.ToSqRefAddress(value);
      _formula = value;
      SetXmlNodeString(FormulaPath, value);
    }
  }

  internal abstract void ResetValue();

  /// <summary>
  /// This value will be stored in the xml. Can be overridden by subclasses
  /// </summary>
  internal virtual string GetXmlValue() {
    if (State == FormulaState.Formula) {
      return ExcelFormula;
    }
    return GetValueAsString();
  }

  /// <summary>
  /// Returns the value as a string. Must be implemented by subclasses
  /// </summary>
  /// <returns></returns>
  protected abstract string GetValueAsString();
}